Electromagnetic relay



June 15 1926. 1,588,604

M.L.NEL$ON ELECTROMAGNETIC RELAY original Filed August 19, 1921 ITLTEW Harhn LNelsmn Patented June 15, 1926.

UNITED STATES PATENT OFFICE.

MARTIN L. NELSON, OF PARK RIDGE, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO AUTOMATIC ELECTRIC INC. OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE- ELECTROMAGNETIC RELAY.

Application filed August 19, 1921, Serial No. 498,630. Renewed November 2, 1935.

The present invention relates in general to electromagnetic relays and has for its object the provision of a new and improved marginal or two-step relay.

Relays of this character have been constructed before and generally have two windings of diflferent magnetizing strengths, or a single winding the magnetizing strength of which can be altered by the introduction of a resistance in series with it or by other appropriate means, the object in any case being to secure either partial or a complete operation of the relay as desired. While these prior arrangements accomplished the desired results it will be appreciated that the operation of a relay so constructed was not as positive as could be desired.

The marginal relay of the present invention was designed with a view to producing a relay whose operation is absolutely positive.

Another object of the invention is to apply this two-step relay to a rotary lineswitch circuit whereby the mechanical interlocking device which has hitherto been necessary between the armatures of the line and switching relays is eliminated and the operation of the circuit improved.

The improved two-step relay in its preferred form is illustrated in the drawing which will now be referred to for a more detailed description of its construction and operation.

Referring now to the drawing, Figs. 2

' and 3 show side and back views, respectively,

of the improved relay. Fig. 1 shows the circuit of the improved rotary lineswitch for an individual subscribers line in an auto matic telephone system using the improved two-step relay.

The operation and the construction of the improved marginal relay will now be described in detail with reference to Figs. 2 and 3. Like parts in the various figures have been given the same reference characters in order to facilitate the explanation. The relay proper is made up of two coils 16 and 17 wound upon the cores 61 and 62, which are attached by means of a single screw 63 to the iron heel piece 41. The heel piece 41 is made so that when the coils 16 and 17 are mounted in place the cores 61 and 62 are the same height but the top of the heel piece 41 is slightly shorter. The armature 47 is mounted on the bracket 65 by means of the flexible spring which is fastened to the bracketat one end by means oi? the screws 45 and 46 and to the armature at the other end. The spring 50 is preferably made of nonmagnetic material. The bracket 65, upon which the armature 47 is mounted, is attached in position on the heel piece 41 by means of the screws 48 and.49. The armature 47 is adapted through the medium of the levers 42 and 43 to operate the springs 21, 22, etc. hen completely assembled the armature 47 is closer to the core 62 than it is to the core 61, as it is pivoted by means of the spring 50 on the bracket 65, which is mounted on the heel piece 41 slightly below the cores 61 and 62. It will be noted that the bracket 65, carrying the armature 47, is mounted on the heel piece 41 by means of the screws 48 and 49 which fit in longitudinally shaped slots in the bracket 65. This construction allows the armature to be very easily adjusted by loosening the screws 48 and 49 and shifting the bracket, without, however, varying the air gap between the armature and the bracket. The movement of the armature is limited by means of the back stop 66 which limits the backward.

movement of the lever 42 and hence the armature 47. There is a similar back stop for the lever 43 which is not shown in the drawing. These backstops are mounted in position by the same screws which hold the relay springs in place.

In order to describe the operation of the improved two-step relay it will be assumed that the coil 17 is energized. When this occurs magnetic flux will be set up in a circuit which includes the core 62 of the coil 17, the heel piece 41, bracket 65, and armature 47. The armature will be attracted against the core 62. A certain amount of flux will be set up in the core 61 of the coil 16, however, this flux will have no appreciable effect on the arn'iature 47 as the core 61 is practically short circuited by the heel piece 41 and bracket 65. Most of the flux will therefore flow through the heel piece and the armature 47 will be attracted until engages the core 62 of the coil 17 and will not engage the core 61 of the coil 16 because, as was before mentioned. the armature 4". on account f the manner in which it is' mounted, is closer to the core 62 than it is to the core 61. lVhen the armature 1-7 is in this position only certain 01" the springs are operated, that is, the spring 20 breaks away from its resting contact but does not engage its working contact, the spring 23 operates in a similar manner. The springs 21 and 22 are not operated at this time. lVhen the winding 16.is energized, which may take place either when the coil 17 is energized or deenergized, as this does not affect the operation, except that if the coil 17 is energized the current flow through the coil 16 must be on the opposite direction to the current flow through the coil-17, armature 47 is fully attracted and changes its tulcrumon the spring 50 from a point close to the heel, piece 11 to the point where it engages the core 62. By this operation springs 20, 22 and 28 engage their working contacts,whilespring 21 breaks away fro nvrits resting contact. The magnetic flux is set up in a circuit which includes the core 61, the core 62, and the armature 47, acertain amount being shuntedby the heel, piece 411.

From the above it will become, apparent that if the coil;17 is energized alone only the springs .20 and 23 are operated, while if the coil 16 is energizedall the springs will be operated. It will,,of course, be understood that any, desired adjustment can be made with. the springs controlled: by the armature 4'7 Without-departing,in any way from the spirit of the, present invention.v

"It will: now, be in order to explain why the spring 50 is made'oit' non-magnetic material. It is some time desirable, to energize the core 16-without deenergizing the coil,l7. Under these conditions it is necessary for the armature 1? to shift its fulcrum as described.

N ow ifthe spring 50 were of magnetic material the armature 47 would tend to stick to the heel piece i1 as there would bepractically. no, air gap between thearmature a7 and the heel piece 4:1 and thus the armature would tend to be prevented from changing its fulcrum. By making the spring 50 of non-magnetic material this ,ditliculty is not encountered.

Having described the construction and operation of the improved two+step i relay, the manner in .whiclra rotary line switch, in which this turo step relay is used, operates will now is described. For this purpose it will now be assumed that a calling subscriber whose line terminates at the exchange in the line switch C, desires to initiate a call. The subscribers substation has not been shown in the vdrawingbut it will belunderstood that this substation is of, the usual automatic type, which, when the receiveris removed,places a bridge across the two line conductors 11 and12 which includes the calling device springs, transmitter and receiver.

1,sse,aoa

Immediately upon this bric ge being placed across the line conductors 11 and 12, a circuit is completed for the line relay l-cl of the line switch C over the two line conductors in series. Relay H, upon energizing, at its armature 25 completes a circuit which includes the two coils 16 and 17 ot' the switching relay 15 and the motor magnet 18 in series, and at its armature 26 connects the test wiper 28 to the above circuit at a point midwaybetweenthe switchingrelay and the said motor magnet. The operation of the line switch C now depends upon whether its switch wipers 27 29, inclusive, are associateduwith an idle trunk line or not. If the associated trunk line is busy, there will be a ground potential present upon the test contact engaged by the test wiper 28, switching "clay 151is shortcii'cuited,andthe motor magnetlS being-supplied with direct ground by way of the said testwiperwill operate as a louzzerto advance the switch wipers step by step in search of an idle trunk line. However, it will be .assumedin thepresent case, when the receireris removed at the calling substation, that theswitch wipers of the line switch C are associatedwith an idletrunl: line and it willbe assumed further that this trunk line is the one shownin the. drawing terminating in bank contacts 30452, inclusive. Under these conditions,v immediately following: the .energication. of the line relay is, the switching relay 15 is energized in serieswith the motor magnet-18. Relay 15, upon operating, at its armature 22 places ground upon the I test contact- ;31, and at its armatures 2O and23 disconnects theline conductors 11 and 12 o'f'thecalling substation from thewindings of;tlie} li ne relay 14 and from ground, respectively, ,and extends by way of wipers 2'1 and 29, banlrcontacts 30 and 32, over the line conductorsot the selected trunk line to 1ll18 1l131361;2l11(l lower windings of t-heline relay of the automatic switch associated with the seized trunk-dine.

Immediately upon, theline conductors being extended to the line relay of the selected switch, this relayis energized over the calling line loop and completes, the circuit of its associated slow acting release relay. latterre lay,upon energizing, prepares the operating circuits of the selected s itch and places ground upontherelcase,trunk couductor oft-he associated trunk line thereby completing a holding circuit for the .line

switch C. This circuit extends from ground on test contact 31, test wiper 26, armature 22v and its front contact,through the windings16 and 17 ofthe switching.relay 15 in series, anchthence through the winding of themotor magnet 18 to battery.- Itwill he understood that the slow acting line relay 1% maintains itsarmature attracted until. this holding circuit is completed. A. branch of this holding circuit also extends byway of the private normal conductor 30 to multiply connected test contacts in the banks of the connector switches which have access to the line of the calling substation whereby the said line is protected from intrusion in the usual manner.

The above is the normal operation of the line switch C when its associated line is calling. When its associated. line is called, upon the connector extending the connection to the line, ground is placed upon the private normal conductor 30 which extends by way of armature 25 and its back contact, back contact and armature 21, through the winding 17 of the. switching relay and thence through the winding of the motor magnet 18 to battery. It will be remenr bered that the coil 17 is only adapted to operate the armatures 20 and 23 of the relay 15 out of engagement with their resting contacts but it does not cause them to engage their working contacts. The other armatures of the relay 15 are not operated at this time due to the novel construction of the improved two-step relay. Consequently, by this operation the line of the called substation is disconnected from its normal battery and ground connections in the line switch C, but is not connected through to the wipers of the switch.

From the above it will be seen that this improved relay construction obviates the necessity of providing a mechanical locking device between the armatures of the line relay 14 and the switching relay 15 in the line switch C. It will, of course, be apparent that this relay is not limited in its application to a rotary lineswitch but may be used wherever a relay having a twostep operation is desired.

The features of the invention having been. fully described and ascertained what is considered to be new and desired to have protected by Letters Patent willv be pointed out in the appended claims.

lVhat I claim as my invention is:

1. In an electromagnetic relay having a pair of coils wound upon different cores at.- tached to a heel piece, an armature adjust ably mounted on said heel piece, said armature being adapted to move on two different fulcrums, means for energizing one of said. coils to cause said armature to move about the end of said heel piece as one fulcrum, and means for energizing the other of said coils to cause said armature to move about the end of the core of the coil first energized as the other fulcrum.

2. In an electromagnetic relay having a pair of coils wound upon dificrent cores, an armature for said relay adapted to move about two different fulcrums, one of said fulcrums being adjustable and the other fixed, the fixed fulcrum being at the end of the first one of said cores, means for energizing the coil wound on said first-core to cause said armature to move on the adjustable fulcrum, and means for energizing the other of said coils to cause said armature to move in the same direction on the fixed fulcrum.

3. In an electromagnetic relay, two separate magnet cores, an armature movable about two diilerent fulcrums by said two cores, respectively, a heel piece and a bracket for suitably supporting said armature adjaccnt said cores, and means for adjusting said bracket on said heel pieceto regulate the normal position of said armature.

4. In an electromagnetic relay, a core and a heel piece mounted substantially parallel to one another, an extension bracket adjustably secured to said heel piece, an armature attached to said bracket and adapted to be moved about a portion of the bracket as a fulcrum when said core is magnetized, and a second core parallel to said first core and adapted when magnetized to move said armature on the extremity of said first core as a fulcrum.

5. In an electromagnetic relay, two n'iagnet cores and a heel piece disposed in parallel planes and magnetically connected at one end, the second core lying between the first core and the heel piece, an armature having two fulcrums, one on the free end of said heel piece and the other on the free end of said second core, said armature responsive to magnetization of said second core to move about the first fulcrum into engagement with the second fulcrum, and responsive to magnetization of said first core to move about said second fulcrum, and means for adjusting the initial position of the said first fulcrum.

6. In an electromagnetic relay, two magnet cores and a heel piece disposed in parallel planes and magnetically connected at one end, the second core lying between the first core and the heel piece, an armature fulcrumed on the free end of said heel piece at a point below the plane of the free ends of said cores, said armature moving on said fulcrum into engagement with the said second core responsive to the magnetization thereof and moving on the end of said second core as a fulcrum responsive to the magnetization of said first core, and means for adjusting the distance between said first ful crum and the plane of the free ends of said cores.

7. In an electromagnetic relay, a flat armature having a support at one end thereof, a core adjacent the center of said armature and adapted to attract the said armature when magnetized, a second core adjacent the other end of said armature and parallel to said first core but shorter, so that the said armature will not engage the second core when the armature is attracted by the first core, and means securing the armature to said support such that when the said second core is magnetized the armature willturn on the end of the first core as a fulcrum.

8. In an electromagnetic relay, two magnet cores and a heel piece disposed in;,parallelplancs, andmagnetically connected at one end, the said heel piece being of such a length that it not intersected by the plane detern'iinedby the free ends of saidcores, and an armatureadjustably supported on the free end of said heel piece and operable either to close the gapbetween the heel piece and one-core orto close the gap be tween the two cores.

9. ln a twostep relay, an armature, an adjustable support for said armature, a magnet core for operating said armature a definitedistance on said support as a fullcrum, cont-act springs actuated by said armature, a second magnet core for causing said armature to-resui'ne its IHOVQIDGDDfOl an additional distance, in ans attaching, said armature to the said support such that the armature is permitted to shiftits fulcrum at, the beginning ofthesecondstage of its movement, and other contactsprings actuated by-said armaturein, the secondlstage of its movement.

10. in an electromagnetic relay, two cores and a heel, piece. disposed in parallel planes,

ture at ,a pointbetweenthe endsoi said.

cores.

In witness whereof, I hereunto subscribe iny-naine-thls 12th.da y .of August, A. 1).,

MAR-TIN ,L. NELSON. 

